Brake boosters of this type are widely used and known. The booster housing of a brake booster of this type in most instances has at least two thin-walled housing shells which are interconnected or intercoupled. Sealing elements which in braking operation are dynamically stressed are disposed between the housing shells and at further locations on the booster housing. The housing shells are in most instances made from a cost-effective, readily formable but corroding thin-walled steel sheet by deep-drawing methods and have to be protected against corrosion.
A so-called cathodic dip-paint coating is widely known as an corrosion protection. This is a paint layer that is applied to deep-drawn and cleaned housing shells by means of a catalytic dipping method. A paint coating of this type has a relatively smooth surface of Rz≅6.3; Ra≅1.2.
In the case of known brake boosters, a number of precautionary measures have to be taken in order to ensure a functionally decisive, permanently reliable sealing in particular in the case of dynamically stressed sealing elements. A solid sealing bead thus has to be provided, for example, in the case of a rolling diaphragm, said solid sealing bead being jammed in a special molding having tight tolerances, i.e. the seal seat, in the housing shells in order for any slipping out, so-called unseating, to be prevented when in operation. At the same time, the rolling diaphragm prior to the assembly has to be pretreated with a separating agent such as talcum, or the like, in order for any undesirable adhesion and the faulty positioning associated therewith to be avoided during assembly. However, the separating agent when in operation increases the risk of the diaphragm slipping out from between smooth painted housing shells.
At the same time, work in the assembling of the brake booster and in particular in the assembly of sealing elements has to be performed very carefully, since the paint layer can be damaged by mechanical influences such as impacts or scratches such that said paint layer flakes at some locations in the sealing region or corrosion is facilitated, the paint layer on account thereof being released from the steel sheet. Leakages which can lead to a reduction in the booster force and therefore are to be avoided can be created on account thereof.